Treatment of synthetic polyamide textile material to improve its moisture absorbency and to reduce its electrification and soiling tendencies



United States Patent Ofiice 3,388,859 Fatented Apr. 36, 1968 3,380,859 TREATMENT OF SYNTHETIC POLYAMIDE TEX- TELE MATERIAL T0 IMPRDVE ITS MGISTURE ABSORBENCY AND TO REDUCE iTS ELECTRE- FICATION AND SOILING TENDENCIES Gwiilym Thomas Jones, John Bryn Owen, and Harold Sagar, Manchester, England, assignors to Imperial Chemical Industries Limited, London, England, a corporation of Great Britain N0 Drawing. Filed June 24, 1964, Ser. No. 377,516 Claims priority, application Great Britain, July 4, 1963, 26,529/63 9 Claims. (Cl. 117138.8)

ABSTRACT OF THE DISCLOSURE A process for treating a synthetic polyamide textile material to increase its moisture absorbency, and to reduce its tendency to electrification and soiling which includes applying to the textile material from an aqueous medium, a hydroxyalkyl derivative of cellulose or starch, a cross-linking agent or a resin precondensate which reacts under acid conditions and a catalyst which is an acid or an acid-generating substance. Thereafter, the treated textile material is dried and heated.

This invention relates to a process for the treatment of textile materials and more particularly it relates to a process for the treatment of synthetic polyamide textile materials.

By synthetic polyamide textile materials we mean in particular those synthetic textile material-s known generically as nylons, which include textile materials composed of polyamides such as polyhexamethylene adipamide and polycaprolactam.

It is well known that synthetic polyamide textile materials are of the class known as hydrophobic, that is to say their capacity for absorbing moisture from the atmosphere is limited, and very much less than that of textile materials composed of natural fibres such as wool and cotton. Largely as a result of their hydrophobic character, synthetic polyamide textile materials readily become electrified when subjected to frictional treatments. Moreover, synthetic polyamide textile materials have a tendency to soil more readily than textile materials composed of natural fibres, and in particular tend to pick up soil from Wash liquors when washed in the presence of other soiled materials. The limited capacity for absorbing moisture, the ready electrification and the increased tendency to soiling are disadvantageous in synthetic polyamide textile materials, especially when they are used for clothing.

Although processes have already been proposed for the treatment of synthetic polyamide textile material in order to increase moisture absorbency and reduce the tendency to electrification and soiling, the effect produced by such treatment is often not permanent and is removed when the textile material is washed.

We have now found that the aforementioned disadvantages may be minimised and that durable effects may be produced on synthetic polyamide textile materials, whereby moisture absorbency is increased and the tendency to electrification and soiling is reduced, by treating the said textile materials with a hydroxyalkylated cellulose or starch and a cross-linking agent or resin precondensate.

Thus according to our invention we provide a process for the treatment of synthetic polyamide textile materials which comprises applying to the said materials from an aqueous medium a hydroxyalkyl derivative of cellulose or starch, 'a cross-linking agent or a resin precondensate which reacts under acid conditions, and a catalyst which is an acid or an acid-generating substance, and then drying and heating.

By a hydroxyalkyl derivative of cellulose or starch we mean cellulose or starch in which at least a part of the available hydroxyl groups have been etherified to give hydroxyalkoxy groups. This etherification may be brought about in known manner by reacting the cellulose or starch under alkaline conditions with an hydroxyalkylating agent such as an alkylene halohydrin or an alkylene oxide. As examples of such hydroxyalkyl derivatives there may be mentioned hydroxyethyl derivatives, hydroxypropyl derivatives and dihydroxypropyl derivatives. Mixtures of such hydroxyalkyl derivatives may be used if desired.

By a cross-linking agent or a resin precondensate which reacts under acid conditions we mean a cross-linking agent which reacts with the hydroxyalkyl derivative of cellulose or starch or with the synthetic polyamide textile material or with both; or we mean a resin precondensate which reacts with itself to give a fully cured resin, or reacts with the hydroxyalkyl derivative of cellulose or starch, or with the synthetic polyamide textile material, or reacts in any combination of these diiierent ways; which reactions are promoted, or at any rate are not inhibited, under acid conditions. Such cross-linking agents and resin precondensa-tes include amongst others: aldehydes and dialdehydes such as formaldehyde, acrolein and glyoxal, capable of cross-linking reactions; the initial stage condensation products of formaldehyde with nitrogen compounds such as urea, thiourea, dicyandiamide, amides, amines, carbamates, aminotriazines, urons, ureins, ureides, imidazolidones, pyridones and triazones, especially the methylol derivatives of such compounds and the lower alkyl ethers of such methylol derivatives; the methylol derivatives of nitrogen containing polymers such as Water-soluble urea/formaldehyde polycondensates, polyacrylamide and addition co-polymers containing acrylamide, and the lower alkyl ethers of such methylol derivatives; and polyacetals such as the ace-tal condensation products of aldehydes such as formaldehyde, acetaldehyde, glyoxal, malondialdehyde, succindialdehyde, adipaldehyde, hydroxyadipaldehyde and terephthalaldehyde with alcohols such as ethylene glycol, diethylene glycol, glycerol, entaerythritol and dipentaerythritol, especially polyacetals of the type described in U.S. Patents 2,785,947; 2,785,948; 2,785,949; 2,785,995; 2,785,996 and 2,786,081. Mixtures of such cross-linking agents or resin precondensates may be used if desired.

As a catalyst in the process of our invention we use an acid or a substance which generates acid at some stage of the process. Since heating synthetic polyamide textile material with strong mineral acid would result in some degradation of the textile material, we prefer to use as catalyst a weakly acid substance or a substance which liberates acid, for example, on heating. As examples of such substances there may be mentioned, amongst others, organic acids such as oxalic acid; salts of weak bases and strong acids such as zinc chloride, the mineral acid salts of organic amines and especially ammonium salts such as ammonium sulphate and ammonium chloride; and substantially neutral substances which develop acidity on heating such as magnesium chloride and ammonium thiocyanate. Mixtures of such catalysts may be used if desired.

The process of our invention may be applied to any textile material composed of a synthetic polyamide. Thus it may be applied to filaments, fibres, tows, yarns, nonwoven webs and woven and knitted fabrics. Moreover it may also be applied to textile materials composed of mixtures of synthetic polyamide fibres with other fibres Whether of synthetic or natural origin.

According to the process of our invention, the hydroxylalkyl derivative of cellulose or starch, the cross-linking agent or resin precondensate and the catalyst are applied to the synthetic polyamide textile material from an aqueous medium, and the material is then dried and heated. The amounts of the different components used in relation to each other and in relation to the weight of textile material to be treated may vary between fairly wide limits. The amounts of the components applied normally lie within the following limits expressed as a percentage of the dry weight of the textile material: the hydroxy alkyl derivative of cellulose or starchbetween 0.1% and 4%; the cross-linking agent or resin precondensate-between 0.01% and 1%; and the catalystbetween 0.01% and 1%.

We have also found that a part of the hydroxyalkyl derivative of cellulose or starch used in the process of our invention may advantageously be replaced by a condensation product of an alkylene oxide with a polyamide. Such a replacement imparts certain advantages, or enables certain disadvantages of the use of a hydroxyalkyl derivative of cellulose or starch alone to be overcome. Thus the use of a proportion of a polyamide/alkylene oxide condensate reduces still further the tendency of the synthetic polyamide textile materials to become electrified when subjected to friction. Moreover, it imparts a soft handle to the said textile material, so offsetting the slightly stiff handle imparted by the use in the process of our invention of the hydroxyalkyl derivative of cellulose or starch alone. Further, in woven or knitted fabrics composed of synthetic polyamide fibres it improves fibre lubrication, resulting in an increase in the strength of the fabric compared with that of similar fabric treated according to the process of our invention using the hydroxyalkyl derivative of cellulose or starch alone.

These condensation products of an alkylene oxide with a polyamide include amongst others those which are described in British patent specification No. 799,153 and in German patent specification No. 907,701. Up to about 50% of the hydroxyalkyl derivative of cellulose or starch may be replaced by the polyamide/alkylene oxide condensate, but we normally prefer to replace between and 25%. The use in the process of our invention of a mixture of a hydroxyalkyl derivative of cellulose or starch with a condensation product of an alkylene oxide with a polyamide instead of a hydroxyalkyl derivative of cellulose or starch alone forms an additional feature of our invention.

The components to be applied to the synthetic polyamide textile material according to the process of our invention, that is to say the hydroxyalkyl derivative of cellulose or starch, the condensation product of an alkylene oxide with a polyamide if such is used, the cross-linking agent or resin precondensate and the catalyst, are dissolved or dispersed in water and the aqueous solution or dispersion is applied to the textile material by any suitable method, for example by impregnating, coating or spraying. If desired minor amounts of surfactants may be incorporated in the liquors to facilitate the wetting out of the textile material. The textile material may then be squeezed if desired to remove any excess liquor, and is then dried. The components are normally applied together from a solution containing all of them, but if desired they may be applied from separate solutions.

After the components have been applied to the textile material it is dried and then heated in order to bring about the desired reactions between the components themselves, or between the components and the textile material or both. If the drying operation is accomplished by heating, as is normally the case, for example by heating within the temperature range 50 C. to 110 C. no further heating may be necessary. It is usually desirable, however, to submit the dried textile material to a separate heating operation. The heating operation may be carried out within a wide range of temperatures, for example at any temperature within the range 50 C. to 230 C., and for a duration of time which may vary between, say, 1 second and 1 hour. Normally the higher thetemperature employed the shorter the time of heating which is necessary.

After the heating operation, the textile material may be rinsed in water and, if desired, washed in a hot solution of a detergent which may also contain an alkali, such as soda ash, to neutralise any residual acidic catalyst. Finally, the textile material may be rinsed with water and dried.

The process of the invention may be applied to the textile materials before, in conjunction with, or after other chemical or mechanical finishing operations such as those used to confer resistance to shrinkage and creasing, modification of handle or surface lustre, water-repelleucy and optical brightness.

Synthetic polyamide textile materials treated according to the process of our invention have increased moisture absorbency, a reduced tendency to soiling and a reduced tendency to become electrified. These desirable properties are not easily destroyed by repeated washing or cleaning operations. Moreover, the treated materials are altered very little in appearance and retain their desirable inherent characteristics such as resistance to creasing or crushing.

The invention is illustrated but not limited by the following examples in which the parts and percentages are by weight.

Example 1 A piece of woven nylon continuous filament fabric was impregnated with an aqueous solution containing 2 parts of hydroxyethyl cellulose, 0.5 part of an etherified polymethylol melamine/urea precondensate prepared as described in Example 10 of British patent specification No. 953,754, 0.2 part of ammonium chloride, and 97.3 parts of Water, and squeezed so as to retain 50% of its weight of liquor calculated on the dry weight of the fabric. After drying at 60 C. the fabric was baked at 150 C. for 3 minutes and finally washed off at 60 C. for 5 minutes in a solution containing 0.1% sode ash and 0.1% of a nonionic detergent, then rinsed with water, and dried.

Compared to an untreated control fabric, the resulting fabric had a reduced tendency to acquire charges of static electricity, a reduced tendency to pick up soil when washed in the presence of soiled fabrics and increased moisture absorbency.

These effects were maintained on repeated washing.

Example 2 A piece of a warp knitted nylon continuous filament fabric was impregnated with an aqueous solution containing 1.6 parts of a hydroxyethylated cellulose, 0.4 part of a polycaprolactam-ethylene oxide condensate containing 2.3% nitrogen, 0.5 part of a ureaformaldehyde condensate prepared as described in Example 2 of British patent specification No. 953,754, 0.2 part of ammonium chloride and 97.3 parts of water, and squeezed so as to retain 50% of its weight of liquor. After drying at 50 C. and baking at 150 C. for 3 minutes the fabric was rinsed with water and dried.

Compared to an untreated control fabric, the resulting fabric had a reduced tendency to acquire charges of static electricity, a reduced tendency to pick up soil when washed in the presence of soiled fabrics and increased moisture absorbency.

These effects were maintained on repeated Washing.

Example 3 A piece of a woven nylon carpet was sprayed with an aqueous solution containing 2 parts of hydroxyethyl cellulose, 0.5 part pentamethoxymethylnrelamine, 0.2 part of ammonium chloride and 97.8 parts of water so that its weight was increased by The piece was then dried at 60 C. and baked at C. for 5 minutes.

Compared to an untreated control piece, the treated carpet had a reduced tendency to acquire charges of static electricity. Furthermore, the ease of soil removal from the treated piece was greatly enhanced.

Example 4 A piece of a nylon continuous filament fabric was impregnated with an aqueous solution containing 1.0 part of hydroxypropyl cellulose, 0.2 part of a water soluble urea/formaldehyde condensate, 0.2 part of tartaric acid, and 98.6 parts of water, and squeezed so as to retain 50% of its dry weight of liquor. After drying, the fabric was baked at 170 C. for 2 minutes, rinsed with water to remove loosely adhering material and dried.

Compared to an untreated control fabric, the resulting fabric had a reduced tendency to acquire and retain charges of static electricity.

This property was substantially maintained after repeated washing.

Example 5 A piece of a nylon warp-knitted shirting fabric was impregnated with an aqueous composition comprising 1.6 parts of hydroxyethyl starch, 0.4 part of a 40% aqueous dispersion of the methylol derivative of a copolymer derived from acrylonitrile and acrylamide, 0.2 part of ammoniurn thiocyanate and 97.8 parts of water, and squeezed so as to retain 50% of its dry weight of liquor. After drying at 70 C., the fabric was baked at 150 C. for 3 minutes.

The resulting fabric, compared to an untreated control fabric, had a reduced tendency to acquire charges of static electricity.

This effect was substantially maintained after repeated washing.

Example 6 In the process of Example 2 the 0.5 part of the urea/ formaldehyde condensate was replaced by 0.5 part of a methylated urea/formaldehyde condensate prepared as described in Example 8 of British patent specification No. 953,754, and a treated fabric was obtained which, compared to an untreated control fabric, had a reduced tendency to acquire charges of static electricity and to pick up soil when washed in the presence of soiled fabrics, and increased moisture absorbency, the effects being maintained on repeated washing.

Example 7 In the process of Example 2 the 0.5 part of the urea/ formaldehyde condensate was replaced by 0.5 part of dimethylol ethyleneurea and a treated fabric was obtained which, compared to an untreated control fabric, had a reduced tendency to acquire charges of static electricity and to pick up soil when washed in the presence of soiled fabrics, and increased moisture absorbency, the effects being maintained on repeated washing.

We claim:

1. Process for the treatment of synthetic polyamide textile materials which comprises applying to said materials from an aqueous medium a mixture of (a) from 0.1% to 4% based on the weight of the material of a hydroxyalkyl compound selected from the class consisting of hydroxyalkyl derivatives of cellulose and starch, (b) from 0.1% to 4% based on the weight of the material of a condensation product of an alkylene oxide with a polyamide, (c) from 0.01% to 1% based on the weight of the material of a compound selected from the class consisting of the methylol derivatives of organic nitrogen compounds containing amino groups and the methylol derivatives of such compounds containing imino groups, the said methylol compound being capable of undergoing reaction with components (a) and (b) above, and (d) from 0.01% to 1% based on the weight of the material of an acid catalyst for the said reaction.

2. The process of claim 1 wherein the component (b) is present in amounts from 10% to 25% of the combined amounts of components (a) and (b).

3. The process of claim 1 in which component (c) is selected from the class consisting of N-substituted derivatives of urea, thiourea, dicyandiamide, amides, amines, carbamates, aminotriazines, urons, ureins, ureids, imidazolidones, pyridones and triazones wherein the substituent has the formula -CH OR in which R is selected from the group consisting of hydrogen or a lower alkyl group.

4. The process of claim 1 in which the condensation product of an alkylene oxide with a polyamide is a condensation product of ethylene oxide with polycaprolactam.

5. The process of claim 1 in which the hydroxyalkyl compound is selected from the class consisting of hydroxyethyl, hydroxypropyl and dihydroxypropyl derivatives of cellulose and starch.

6. The process of claim 1 in which component (c) is selected from the class consisting of N-substituted derivatives of water soluble urea/formaldehyde polycondensates, polyacrylarnide and addition copolymers containing acrylamide, wherein the substituent has the formula CH OR in which R is selected from the group consisting of hydrogen or a lower alkyl group.

7. The process of claim 1 in which the catalyst is a Weakly acid substance.

8. The process of claim 1 in which the catalyst is a substance which liberates acid on heating.

9. The process of claim 1 in which heating is carried out within the temperature range C. to 230 C. for from 1 second to 1 hour.

References Cited UNITED STATES PATENTS 2,370,517 2/1945 Bass et al. 260-15 2,469,431 5/1949 Broderick 260-15 2,978,359 4/1961 Wedell 117l38.8 2,998,295 8/1961 Goldann 117-138.8

WILLIAM D. MARTIN, Primary Examiner.

R. HUSACK, Assistant Examiner, 

